Three clones for structural genes coding for proteins secreted from the rat ventral prostate have been identified by hybrid arrest translation. The three cloned inserts have been mapped with restriction endonucleases, and the homologous mRNAs have been shown to be induced by androgens. A rat gene library carried in lambda phage charon 4A is currently being screened for the genomic sequences corresponding to two of the secreted proteins. In addition, total poly(A+)-mRNA from human prostate tissue has been cloned using the E. Coli-PBR322 system. These clones are currently being screened for the structural gene corresponding to a major secretory protein previously identified by two-dimensional gel electrophoresis of human prostatic fluids.